Apparatus for providing a CPU cluster via a disk I/O bus using a CPU brick which fits into a disk cavity

ABSTRACT

A general purpose computer apparatus including a central processing unit, a main memory and a system bus. The general purpose computer apparatus further includes means for interfacing the central processing unit to the system bus and means for interfacing the central processing unit to an I/O bus. A housing encloses the central processing unit, the main memory and the means for interfacing, with the housing having a mechanical form factor corresponding to a disk drive housing.

BACKGROUND OF THE INVENTION

This invention relates generally to computer systems and moreparticularly to clustered computer systems.

As is known in the art, a computer system is generally comprised of acentral processing unit (CPU), a memory unit, at least one input/outputdevice, and a bus which is used to connect the aforementioned devices.The computer is housed in a cabinet which contains a power supply tosupply power for the various components of the computer. In operation,the central processing unit fetches and decodes incoming instructions,executes commands, and manipulates data, while the memory unit, which iscomposed of multiple storage locations, stores data to be used by theCPU. The I/O device is generally used to input data to and output datafrom the computer system. Typical types of I/O devices include printers,keyboards, displays and mass storage units such as disk drives etc.These devices are often interfaced to the computer-system with an I/Ointerface controller circuit.

Often, a user's processing needs will grow beyond the capabilities of asingle CPU. In an effort to meet these new processing needs, computersare typically clustered to make a plurality of CPUs available forprocessing. A clustered computer system is an integrated group ofcomputers that communicate over a high-speed communication path. Theclustered computer system acts as a single system to users. That is,clustered computer systems are characterized by a high degree oftransparent resource sharing, which includes access by each individualcomputer system to storage located anywhere in the clustered system, andincreased processing throughput.

In a typical cluster, there are two or more CPUs sharing inter alia atleast one common system disk. Using multiple CPUs in a clusteredconfiguration enables processing time on the CPUs to be used moreefficiently. Thus, it affords the user better performance when jobs arerun on a clustered system.

At least one additional general purpose computer is necessary to providea clustered configuration for a computer system. Depending upon thecharacteristics of an existing system it may be possible to acquire anadditional CPU and associated cabinet and power supply and interconnectthese devices with the existing equipment. The two systems are connectedthrough the additional cables and harnessing and are configured usingsoftware to behave as a clustered computer system. While the existingequipment and acquired general purpose computer system will provide aclustered computer system there are several drawbacks to this approach.For example, included with each general purpose computer system is apower supply and the cabinet as well as additional hardware such ascables and harnessing to connect the two computer systems. Clusteringcomputer systems using this approach provides a redundancy in thehardware of the computer system, but at a substantial increase in costparticularly for the mechanical components necessary to provide theclustered system. Moreover, by providing separate cabinets, longercables and harnesses are needed to interconnect the systems. This limitsthe maximum number of systems which can be interconnected, particularlyfor executing bus specification protocols, due to electrical timing andparameter considerations.

Another option available to provide additional processing power ismultiprocessing. A single processing board can be used which includesmultiple CPUs. This option however is not only costly but it assumes theuser has foreseen a future need for an increase in processing power.

SUMMARY OF THE INVENTION

In accordance with the present invention, a general purpose computerapparatus includes a central processing unit, a main memory, and asystem bus. The general purpose computer apparatus further includesmeans for interfacing the central processing unit to the system bus andmeans for interfacing the central processing unit to an I/O bus. Thegeneral purpose computer system further includes a housing enclosing thecentral processing unit, the main memory and the means for interfacingwith the housing having a mechanical form factor corresponding to a diskdrive housing with such an arrangement, the general purpose computerapparatus is housed in a chassis or housing which can be disposed withina disk drive slot of a standard general purpose computer cabinet. Byappropriate interconnect and configuration of the apparatus with asecond general purpose computer in the general purpose computer cabineta clustered computer system can be provided.

In accordance with a further aspect of the present invention, a computersystem includes a cabinet having at least one slot for receiving a diskdrive, and a first general purpose computer apparatus disposed in thecabinet. The first general purpose computer apparatus includes a firstcentral processing unit, a system bus, and an I/O interface modulecoupled to said system bus for interfacing said system bus to an I/Obus. The computer system further includes a second general purposecomputer apparatus which includes a second central processing unit, amain memory, and means for interfacing the second general purposecomputer apparatus to the first general purpose computer apparatus. Thesecond general purpose computer apparatus further includes a housingenclosing the second general purpose computer apparatus, the housinghaving a mechanical form factor corresponding to the slot for receivinga disk drive, with the housing disposed in the slot. With such anarrangement a clustered computer system configuration may be provided byappropriate interconnect and configuration of the second general purposecomputer apparatus with the first general purpose computer in thegeneral purpose computer cabinet while saving the cost of an additionalcabinet, power supply, cabling and harnessing. In addition, since thelength of cabling will in general be shorter than prior approaches, moresystems can be clustered on one bus. For example, if the systems areclustered over a DSSI bus, a total of eight systems may be clusteredwithout violating electrical specifications for DSSI bus clusters ratherthan the maximum of three systems when the systems are housed inseparate cabinets and longer lengths of cabling are necessary tointerconnect the systems.

In accordance with a further aspect of the present invention, a computersystem includes a cabinet for housing the computer system, the cabinethaving a panel with at least two openings in the panel of the cabinet.The computer system further includes a power supply disposed within thecabinet and a first general purpose computer disposed within thecabinet. The first general purpose computer further includes a firstcentral processing unit module, including a central processing unit, amain memory, an I/O adapter interface, and a system bus coupling thefirst central processing unit module to the main memory and the I/Oadapter interface. The computer system further includes a disk drivedisposed in a first one of the openings in the panel of the cabinet anda second general purpose central processing unit module disposed in asecond one of the openings in the panel of the cabinet and coupled tothe cabinet by the corresponding receiving means. The second generalpurpose central processing unit module further includes a control panelhaving at least one switch which is used to reboot the second centralprocessing unit module. The first central processing unit module and thesecond central processing unit module receive power from the powersupply. With such an arrangement the existing equipment may be connectedto the general purpose central processing unit module to provide amultiprocessing system thus, saving the user the cost of a completemultiprocessing system as well as in some cases protecting an investmentmade in existing equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features of the invention will now becomemore apparent by reference to the following description taken inconnection with the accompanying drawings in which:

FIG. 1 is a block diagram of a general purpose, clustered computersystem;

FIG. 2 is an isometric view of a computer system cabinet housing thegeneral purpose, clustered computer system of FIG. 1;

FIG. 3 is an exploded view of a general purpose computer brick;

FIG. 4 is an isometric cutaway view of the general purpose computerbrick of FIG. 3 showing inner components of the brick;

FIG. 5 is a block diagram representing the partitioning of the modulesof the general purpose computer brick; and

FIG. 6 is an isometric view of the general purpose computer brickdepicting a relationship between the apertures in the enclosure of thebrick and notches in printed circuit boards disposed in the enclosure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, a general purpose, clustered computer system 10is shown to include a general purpose computer 11 having inter alia aCentral Processing Unit (CPU) 12, a system memory 13, I/O 16 and an I/Obus adapter 15 all interconnected via a system bus 14. CPU 12 typicallyincludes a microprocessor device, interface circuits and timing andcontrol circuits and is used to process computer instructions, generallyfetched from system memory 13, in a predetermined manner to completesome computer processing task. System memory 13 typically includes aplurality of integrated circuit memory devices such as dynamic randomaccess memory (DRAM) or static random access memory (SRAM) which providemain data storage for the CPU. The I/O bus adapter 15 is further coupledto two disk drives 17 and 18 through an I/O bus 20.

The general purpose, clustered computer system further includes a secondgeneral purpose computer 19 including a CPU 21, a system memory 22, I/O23 and an I/O bus adapter 24 each communicating through a system bus 25.In general the second general purpose computer system 19 providessimilar functionality as general purpose computer system 11. Furtherincluded in the second general purpose computer 19 is an operatorcontrol panel 26 which provides an operator control over the secondgeneral purpose computer 19. The clustered general purpose computer isalso shown to include a single power supply 27, which provides allappropriate voltages such as five volts for the logic devices and twelvevolts for the electromechanical devices in the disk drive. That is thepower supply here supplying power to each module of the first generalpurpose computer as well as to each of the disk drives and each moduleof the second general purpose computer 19. General purpose computer 11and general purpose computer 19 are logically connected through aDigital Storage System Interconnect (DSSI) Bus 28 here referred to asDSSI bus_0.

Referring now to FIG. 2, a system cabinet 30 to house the generalpurpose, clustered computer system of FIG. 1 is shown. The first generalpurpose computer system 11 and power supply 27 are housed within thelower portion of the cabinet here depicted by modules 35 a-35 g. Thepower supply 27 is depicted here as being located in the right handportion 36, as shown. The cabinet 30 further has openings to accommodatehere, three disk drives. Housed in one of the disk drive openings is thesecond general purpose computer 19 including the CPU module, the memorymodule, the system bus, and the I/O adapter interface as discussed aboveappropriately packaged 32. Here, shown housed in one of the remainingdisk drive openings, is a disk drive 31. The third disk drive slot 33 isshown empty. Also shown included in the system cabinet 30 is a tapedrive 34. The packaged 32, second general purpose computer system 19 ofFIG. 1, is located within the disk drive opening and is physically andlogically connected through the standard disk drive connections,including power and an I/O bus capable of supporting CPU to CPUcommunication protocol. Examples of bus protocols include a system busprotocol, a network protocol and an I/O bus protocol. Preferably, thebus protocol is the Digital Storage System Interconnect (DSSI).

A DSSI bus is a general purpose communication bus. The DSSI bus is usedto connect host computers and storage devices. It is similar in functionto a Computer Interconnect (CI) bus protocol which is used forinterconnecting medium to large computer systems into clusters. The DSSIbus, like the CI bus, operates using the System CommunicationArchitecture protocols. The DSSI bus is the preferable bus because itoperates at a high level thus handling error conditions moreeffectively. Because the electrical specifications for a DSSI buscluster are very stringent regarding the lengths of the electricalpaths, the maximum number of nodes on a DSSI bus cluster is three when atypical configuration using separate cabinets for each system is used.By connecting additional general purpose computer systems through theDSSI ports in the disk drive slots, shorter electrical paths result,thus allowing the maximum number of general purpose computer systemswhich may be connected through this process to increase up to eight.

Through these connections and some additional clustering software, thegeneral purpose computer system apparatus is connected in a clusterconfiguration with the general purpose computer housed within the maincabinet.

Referring now to FIG. 3, the second general purpose computer system 19is packaged in a configuration adapted to be mounted in a standard 5¼inch disk drive opening. The enclosure for the second general purposecomputer 19 is shown to include a vented side panel 42 a which allowsair flow through the apparatus. A portion of the panel 42 b is bent atan angle orthogonal to the air vented portion of the panel and includesfive apertures 54 a-54 e through which the second general purposecomputer system 19 receives connections from the general purposecomputer system 11 for DSSI bus_0, a Small Computer System Interconnect(SCSI) bus and a Q bus. Through two of the apertures 54 b, 54 c thesecond general purpose computer system also receives power from thepower supply 27. The opposing side of the general purpose computerapparatus is shown as a solid metal chassis having a pair of side panels41 a, 41 b bent at an angle such that the panels 41 a, 41 b are mutuallyparallel and orthogonal to the base member 41 c. The side panels 41 a,41 b have guides 55 which will position here three printed circuitboards 43, 44, 45 disposed within the metal enclosure. Also located onthese two side panels 41 a, 41 b are three pairs of rectangularapertures 52 a′, 52 a″, 52 b′, 52 b″, 52 c′, 52 c″.

At a first end of the general purpose computer apparatus 40 is an area56 through which access is available to a locking connector disposedwithin the metal enclosure of the general purpose computer apparatus 40.This locking connector accepts a ribbon cable input located on the backof the control panel 26. Secured to two of the sides of the metalenclosure is additional air vented bracketing 50, 51 which allows thepackaged general purpose computer 32 to be inserted into a disk driveopening in a system cabinet 30 as shown in FIG. 2. Further included atone end of the metal enclosure are connectors 46 which the printedcircuit boards are plugged into. Additional connectors are found at theopposite end of the CPU module 57, a mate and lock connector 48 toconnect to the power supply 27 and a ribbon cable connector 47 withlocking tabs to connect to the DSSI bus_0 28 and the SCSI bus of generalpurpose computer system 11. The opposing end of each of these connectorsplugs into a paddle card 49 which physically connects to the backplanewithin the disk drive slot and logically connects to the SCSI bus andthe DSSI bus_0 28 of general purpose computer system 11. Shown is atypical configuration including two DSSI buses, a SCSI bus, a Q buswhich is a general purpose I/O bus and an NI bus or ETHERNET bus whichis a network bus as will be mentioned. Other configurations of coursecould be used, provided a bus is made available to interconnect thefirst general purpose computer to the second general purpose computer.

Referring now to FIG. 4 the assembled general purpose computer 19packaged as a computer “brick” 32 is shown to include a CPU module 21,an I/O module 23 and eight single inline memory modules plugged at anangle into a memory carrier 22. The CPU module 21 is partitioned tocontain the logic for the CPU, the DSSI bus_0 28 and the networkinterconnect. The I/O module 23 is partitioned to include the logic forI/O operations, DSSI bus_1 and Q bus. The CPU module 21, the I/O module23 and the memory carrier 22 are each provided with notches 53 a′, 53a″, 53 b′. 53 b″, 53 c′, 53 c″ on the edges of the printed circuit boardto be used in removing the individual boards from the enclosure as willbe described.

Cabling to connect the general purpose computer brick to the existinggeneral purpose computer system housed within the existing cabinet isfed through five apertures 54 a-54 e at one end of the general purposecomputer brick's enclosure. Connections are made to power, DSSI bus₀ 28,SCSI and Q bus through these five apertures 54 a-54 e. On the oppositeend of the brick from these apertures, the operator control panel 26 isconnected using a high density ribbon cable 61 into a connector on thegeneral purpose computer brick which includes locking tabs. The operatorcontrol panel 26 includes a network interconnect BNC connector 60 herefor an NI or ETHERNET bus and a console port. Also included are a resetbutton (reboot) 66, a halt button 65 and a halt enable switch 62. Twohigh density dual in-line (DIN) connectors 65, 66 are also includedthrough which peripherals may be connected to the general purposecomputer brick's 32 DSSI bus₁. The operator control panel also includesa diagnostic display 67 to display any errors the general purposecomputer brick 32 might encounter.

Referring now to FIG. 5, the partitioning of the CPU 21, the I/O 23 andthe memory modules 22 of FIG. 4 are shown to include the systemmicroprocessor 70, I/O 71 and memory control 72 and a Single HostAdapter Chip (SHAC) for the DSSI bus_0 interface 73 and a SecondGeneration Ethernet Chip (SGEC) Network Interconnect interface 74 in theCPU module 21. The memory control 72 on the CPU module 21 is connectedinto the memory module 22 which includes the memory carrier 75 and thesingle inline memory modules 76 a- 76 h which provide the main systemmemory. The I/O control 71 of the CPU module 21 is connected into theI/O module 23 which is partitioned to include the read only memory forthe bootstrap and diagnostics code 77. Further included in thepartitioning of the I/O module 23 is the system support chip 78 and thenon-volatile Random Access Memory 79. Interface logic is also includedfor an SCSI Bus 81, a Q bus 82 and a SHAC for DSSI Bus 1 80 on the I/Omodule 23.

Referring now to FIG. 6, the brick is shown to include pairs ofrectangular apertures 52a′, 52a″ in proximity to pairs of notches 53b′,53b″ on edges of the printed circuit boards 21, 22, 23. When the printedcircuit boards 21, 22, 23 are in place within the enclosure of thegeneral purpose computer brick 32 the pair of notches 53 a′, 53 a″ onopposing edges of the circuit boards are aligned with apertures 52 a′,52 a″ within the sides of the brick 32. Here the apertures 52 a′, 52 a″are rectangular but of course other shaped apertures could be used. Twoflat-headed screwdrivers (not shown) are inserted through therectangular shaped apertures 52 a′, 52 a″ into one of the pair ofcorresponding notches 53 a′, 53 a″ in the circuit board 21 and pressureis placed against the side of the notch to pry or pop the circuit boardfrom its connector. Because of the distance the circuit board musttravel in order to be completely freed from the connector, it ispreferred to have two rectangular apertures as well as two notchesprovided in order that the necessary travel may be achieved. The notchesare placed in the circuit boards such that when the circuit board is inplace within the enclosure half of one of the notches is visible throughthe rectangular aperture and the second notch is hidden behind the spacebetween the two apertures.

Having described preferred embodiments of the invention, it will nowbecome apparent to those of skill in the art that other embodimentsincorporating its concepts may be provided. It is felt therefore thatthis invention should not be limited to the disclosed embodiments butrather should be limited only by the spirit and scope of the appendedclaims.

What is claimed is:
 1. A general purpose computer apparatus comprising:a central processing unit; a main memory; a system bus; first means forinterfacing said central processing unit to said system bus; secondmeans, coupled to said system bus, for interfacing said centralprocessing unit to an I/O bus; and a housing enclosing said centralprocessing unit, said main memory, said system bus and said first andsecond means for interfacing, said housing having a size and a shape sothat the housing can be physically mounted in a disk drive slot of acomputer system, and including a control panel disposed over a portionof said housing, said control panel having at least one switch with saidswitch being used to reboot said central processing unit, wherein saidsecond means for interfacing supports a bus protocol that allowscommunications from one central processing unit to a second centralprocessing unit.
 2. The apparatus of claim 1 wherein said bus protocolis a system bus protocol.
 3. The apparatus of claim 1 wherein said busprotocol is an I/O bus protocol.
 4. The apparatus of claim 3 whereinsaid bus protocol is a Digital Storage System Interconnect protocol. 5.The apparatus of claim 3 wherein said bus protocol is a Small ComputerSystem Interconnect protocol.
 6. The apparatus of claim 1 wherein saidbus protocol conforms to an Ethernet protocol standard.
 7. A computersystem comprising: a cabinet having at least one slot for receiving adisk drive; a first general purpose computer apparatus disposed in saidcabinet, said first general purpose computer apparatus including: afirst central processing unit; a system bus; an I/O interface modulecoupled to said system bus for interfacing said system bus to an I/Obus; and a second general purpose computer apparatus including: a secondcentral processing unit; a main memory; means for interfacing saidsecond general purpose computer apparatus to said first general purposecomputer apparatus; and a housing enclosing said second general purposecomputer apparatus, said housing having a size and shape so that thehousing can be physically mounted in said slot for receiving a diskdrive, with said housing disposed in said slot.
 8. A computer system asin claim 7 wherein said means for interfacing provides for communicationbetween said first general purpose computer apparatus and said secondgeneral purpose computer apparatus.
 9. A computer system as in claim 7wherein said means for interfacing provides for communication betweensaid first central processing unit and said second central processingunit.
 10. A computer system as in claim 7, said means for interfacingcomprising means for interfacing said second central processing unit tosaid I/O interface module of said first general purpose computerapparatus.
 11. A computer system as in claim 7, said second generalpurpose computer apparatus further including: a control panel disposedover a portion of said housing, said control panel having at least oneswitch.
 12. A computer system as in claim 11, wherein said switch isused to reboot said second central processing unit and said firstgeneral purpose computer apparatus further including a second switch,said second switch being used to reboot said first central processingunit.
 13. A computer system as in claim 7 further including: a powersupply disposed in said cabinet wherein said power supply provides powerto said first general purpose computer apparatus and said second generalpurpose computer apparatus.
 14. A computer system comprising: a cabinetfor housing said computer system, said cabinet having a panel with atleast two disk drive openings in said panel of said cabinet; a powersupply disposed within said cabinet; a first general purpose computerdisposed within said cabinet further comprising: a first centralprocessing unit module including a central processing unit; a mainmemory; an I/O adapter interface; a system bus coupling said firstcentral processing unit module to said main memory and said I/O adapterinterface; a disk drive disposed in a first one of said disk driveopenings in said panel of said cabinet; a second general purpose centralprocessing unit module disposed in a second one of said disk driveopenings in said panel of said cabinet; and a control panel having atleast one switch which is used to reboot said second central processingunit module; wherein said first central processing unit module and saidsecond central processing unit module receive power from said powersupply.